Gas powered guns of the above mentioned kind are well known in the art, and the compressed gas may be e.g., air (air guns).
The tension of the spring will determine the force of the hammer, and thus the time during which the valve is open. The stronger the spring force, the longer the valve will stay open, and the more gas will be exhausted into the barrel. And the more air, the higher speed of the discharged projectile.
Therefore, it is known to adjust the tension of the spring, typically by moving the spring abutment against which the spring rests. Typically such adjustment requires specific tools, and is only done during manufacturing.
However, there is an increased need or desire to provide more simple adjustment of the discharge speed.
General Disclosure of the Invention
This and other objects are achieved by a gas powered gun for discharge of projectiles, comprising a valve arranged to exhaust compressed gas from a chamber to thereby discharge a projectile inside a barrel, a hammer arranged to be cooperate with a valve opening arrangement to thereby open the valve, a movable spring abutment, and a spring arranged between the hammer and the spring abutment and arranged to spring load the hammer in a spring loading direction towards the valve opening arrangement. The gun further comprises an adjustment knob including a gripping portion, allowing a user to grip the adjustment knob and to turn the adjustment knob around an axis of rotation, the axis of rotation being substantially perpendicular to the spring loading direction, and a cam surface extending around the axis of rotation and having a varying radial distance from the axis of rotation, and a follower, integrated with the spring abutment and pressed by the spring in the spring loading direction to rest against the cam surface, so that, when the adjustment knob is turned, the follower will slide against the cam surface and move the follower and the spring abutment in the spring loading direction, to thereby adjust a pretension of the spring
According to the invention, the spring abutment, and thus the compression of the spring, can be easily adjusted by turning the knob. More specifically, depending on the rotational position of the knob, the portion of the cam surface facing the follower will have a different distance to the axis of rotation, and the follower, which is pressed against the cam surface, will thus assume a different position in the spring loading direction. As the abutment is attached to the follower, also the position of the abutment will be changed. The position of the abutment will determine a distance between the abutment and the hammer, and thus the compression of the spring. The compression of the spring will determine the force of impact of the hammer on the valve opening arrangement, which in turn will determine the duration of time during which the valve is open. The longer the valve is open, the more compressed gas will enter the barrel, and the higher the velocity of the discharged bullet will be.
The expression “coupled with” is intended to include all designs where movement of the follower will lead to movement of the abutment. For example, the abutment and follower may integrally formed as one single element. They may also be formed as two elements, fixedly attached to each other. More complex alternatives are also possible, where the follower and abutment are mechanically linked by intermediate members.
The knob is preferably arranged so as to be easily accessible from outside the gun, i.e. without requiring any dismantling of the gun or any special tools.
The cam surface may be the mantle surface of a cylindrical portion formed with a center axis in parallel and at a distance from the axis of rotation. This is a simple and effective way to design and manufacture a knob with a cam surface according to the invention. It means that the cylindrical portion is asymmetrically arranged around the axis of rotation of the knob.
The knob can be lockable in predefined positions, each position associated with a specific portion of the cam surface facing the follower, each cam surface portion having a specific distance to the axis of rotation. This makes it very easy for a user to select a desired velocity by turning the knob to one of the positions. For example, the knob may include a plurality of indentations in a surface facing the gun, and a spring loaded rounded surface arranged to slide against the surface and to engage one of the indentations, to thereby lock the knob in one of the plurality of predefined positions.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the [element, device, component, means, step, etc.]” are to be interpreted openly as referring to at least one instance of said element, device, component, means, step, etc., unless explicitly stated otherwise.